Infrared and acoustic emission monitoring rock true triaxial fast unloading confining pressure test system and method

Abstract

An infrared and acoustic emission monitoring rock true triaxial rapid unloading confining pressure test system and method. Mainly include: rigid pressure loading system, air pressure control system, gas confining pressure chamber, infrared observation system. The vertical loading system provides Z direction load; the lateral loading system provides Y direction load; the external gas source provides gas pressure, enters the gas pressure chamber through the floor gas pipeline, provides X direction load; the gas pressure chamber X direction is provided with front and rear infrared observation windows, both are CaF2 glass materials, can erect infrared thermal imager to realize infrared observation; the loading plate can be built-in acoustic emission probe through the detachable structure. The present application uses the pressure head and the pressure plate to provide the pressure in Y direction and Z direction through special design, uses the gas to supply the pressure in X direction, can realize the X direction rapid unloading, and solves the problem that the infrared visualization is difficult to realize in the true triaxial compression test process. Through the detachable design of the loading plate, the acoustic emission probe can be built-in.

Description

Technical Field

[0001] This invention belongs to the field of mining rock mechanics and engineering technology, specifically relating to a rapid triaxial unloading confining pressure test system and method for rock using infrared and acoustic emission monitoring. Background Technology

[0002] In the field of mining rock mechanics research, the mechanical testing of rock samples occupies an extremely important position. True triaxial testing plays an indispensable role in this. Compared with conventional triaxial testing, true triaxial testing can control the magnitude of triaxial stress. Rapid unloading of confining pressure can simulate dynamic disasters such as rock bursts and rockbursts caused by the transient release of surrounding rock stress induced by the excavation of underground engineering (tunnels, mining) in high-stress areas. It can more realistically simulate the evolution of stress paths under complex geological conditions and further explore the mechanical properties and failure mechanisms of coal and rock masses.

[0003] Rock fracture is the result of the accumulation of internal microcracks, and the crack propagation process releases various types of signals. Using infrared and acoustic emission methods, the crack propagation state of a sample under load can be monitored in real time and non-destructively. Therefore, developing a true triaxial rapid unloading confining pressure testing system for rocks using infrared and acoustic emission monitoring is of great significance.

[0004] Currently, in true triaxial tests, rock samples are sealed, making it impossible to use infrared methods to observe the crack propagation state on the sample surface in real time. Chinese patent CN201610155869.2 discloses an acoustic emission testing device that integrates an acoustic emission sensor into a true triaxial chamber, introducing a method of embedding the acoustic emission probe within the sample clamp with the signal line leading out from inside the clamp. However, this method makes disassembling the acoustic emission probe difficult and cannot achieve rapid release of confining pressure. Chinese patent CN201711430420 discloses an acoustic emission monitoring unit for a true triaxial mining-induced coal and rock dynamic manifestation experiment, introducing a method of embedding the acoustic emission probe within a loading plate without affecting the intended function. However, the acoustic emission probe can only be placed in a fixed position at the edge of the loading plate, and the bolted connection makes disassembly inconvenient. Chinese patent CN202010870243.6 discloses a simulated triaxial acoustic emission strain field joint observation device, which introduces a sensor coupling fixing component that can place the acoustic emission probe on the edge of the loading plate on the left and right sides. The pin structure restricts the acoustic emission position for easy disassembly, but it cannot achieve true triaxial loading and the acoustic emission probe can only be arranged on the edge of the sample.

[0005] In summary, current true triaxial testing equipment cannot achieve rapid unloading of confining pressure and is difficult to perform infrared observation. There is a lack of a simple loading plate device that can place the acoustic emission probe at different positions on the sample, making it impossible to achieve rapid unloading of confining pressure for infrared and acoustic emission monitoring under true triaxial testing. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a rapid triaxial unloading confining pressure test system and method for rocks using infrared and acoustic emission monitoring.

[0007] To achieve the above objectives, a true triaxial rapid unloading confining pressure test system for rocks with infrared and acoustic emission monitoring is proposed, including a rigid loading system, a gas pressure control system, an infrared monitoring system, an acoustic emission data monitoring system, an LVTD monitoring system, and a gas confining pressure chamber;

[0008] The rigid loading system includes a Z-axis press frame, a Z-axis loading system, a Y-axis press frame, a Y-axis loading system, and a pressure data acquisition computer;

[0009] The air pressure control system includes air pressure pipelines, pressure data sensors, air tank inlet valves, pressure relief valves, and air pressure data acquisition computers;

[0010] The infrared monitoring system includes infrared thermal imager I, infrared thermal imager II, and infrared data acquisition computer;

[0011] The LVTD monitoring system includes an LVTD data transmitter and an LVTD data acquisition computer;

[0012] The acoustic emission data monitoring system includes an acoustic emission probe module and an acoustic emission data acquisition computer;

[0013] The gas confining chamber includes a top cover, side walls, and a bottom plate. The top cover has a Z-direction pressure head channel connecting the inside and outside of the gas confining chamber, and a Z-direction extrusion rod with a pressure head at its front end is movably mounted within the Z-direction pressure head channel. Infrared observation windows are installed on the X-direction side walls, and Y-direction pressure head channels are opened on the Y-direction side walls, with a Y-direction extrusion rod with a pressure head movably mounted within the Y-direction pressure head channels. Sealing elements are installed in both the Y-direction and Z-direction pressure head channels. The upper part of the bottom plate has a sample stage, an acoustic emission integrated interface, and an LVTD integrated interface. The bottom plate contains an air inlet channel, an LVTD signal channel, and an acoustic emission channel. An air inlet communicating with the air inlet channel is opened at the top of the bottom plate. A threaded channel is provided at the top of the Z-direction extrusion rod. An exhaust port connecting the inside and outside of the gas confining chamber is provided on the top cover. A base is located at the center of the upper part of the bottom plate, and the sample stage, acoustic emission integrated interface, and LVTD integrated interface are all located on the base.

[0014] The top cover and bottom plate are connected by large bolts, while the side plates are sealed between the top cover and bottom plate. The rear pressure relief port of the air intake channel is connected to the gas tank through a gas pressure pipeline to provide X-axis air pressure. The front air intake port of the air intake channel is connected to a pressure data sensor, which is connected to a gas pressure data acquisition computer for real-time monitoring of the internal air pressure of the gas confining chamber. The acoustic emission channel is connected to an acoustic emission data acquisition computer, and the LVTD signal channel is connected to an LVTD data acquisition computer, enabling real-time monitoring of acoustic emission, infrared, and pressure data during the loading process.

[0015] The acoustic emission probe module is connected to the acoustic emission channel.

[0016] Furthermore, the acoustic emission probe module includes a loading plate, an acoustic emission probe, and a pair of loading frames. The loading plate has a pair of vertically arranged frame grooves at its rear, each capable of housing an acoustic emission probe, which is then positioned by the loading frames. The loading frames corresponding to the upper frame groove have spring-supported buckles at their lower ends, and the loading frames corresponding to the lower frame groove have spring-supported buckles at their upper ends. The upper frame groove has a buckle channel on its bottom surface, and the lower frame groove has a buckle channel on its top surface. When the acoustic emission probe is connected to the loading frame, a rubber pad and a spring are sequentially arranged from the acoustic emission probe end to the rear of the loading frame. The frame grooves can embed the loading frame, and the loading frame is fixed by embedding the buckles into the buckle channels.

[0017] The loading plate has a pair of side buttons on both sides, corresponding to four latching channels. The loading plate has an internal cavity, in which gears corresponding to the side buttons are rotatably installed. Each latching channel has a top column slide rail installed along the channel. A top column is slidably installed on the top column slide rail. One side of the top column has a meshing protrusion that meshes with the gear. The bottom of the top column is connected to a tension spring through a top column hook. The other end of the tension spring is connected to the bottom of the latching channel. The side buttons are connected to the gears through hinges.

[0018] A rapid triaxial unloading confining pressure test method for rocks using infrared and acoustic emission monitoring includes the following steps:

[0019] Step 1: Screw the lifting ring into the threaded channel of the top cover, control the robotic arm to lower the hook, and lift the top cover and the gas-contained pressure chamber;

[0020] Step 2: Connect the acoustic emission probe to the wires, and place the rubber pad and spring in sequence at the rear of the acoustic emission probe. Press the buckle and place the loading frame in the slot of the frame. After the loading frame fits with the loading plate, the front port of the acoustic emission probe is exposed. Insert one Z-axis loading plate and two Y-axis loading plates into the pressure head of the Z-axis extrusion rod and the Y-axis extrusion rod respectively. Connect the wires connected to the acoustic emission probe to the acoustic emission integrated interface of the base.

[0021] Step 3: Adhere the strain gauge to the Y-axis surface of the specimen, install the prepared specimen onto another Z-axis loading plate, place the whole specimen on the specimen stage, adjust the position (after the probe is installed on the loading plate, the probe end is just the end that contacts the specimen wall), and fasten the loading plates on the pressure heads of the Z-axis extrusion rod and the Y-axis extrusion rod to the loading plate on the specimen stage, and connect the strain gauge wires to the LVDT integrated interface.

[0022] Step 4: Control the robotic arm to lower the top cover and the gas confining chamber, screw the large bolt into the bolt hole of the base plate, tighten it, and let it stand still on the slide rail of the rigid loading system until the sample and the confining gas adsorption reach equilibrium and the temperature is the same as the overall system temperature.

[0023] Step 5: Connect the acoustic emission data acquisition computer and the LVDT data acquisition computer. Set up infrared thermal imager I and infrared thermal imager II on both sides of the infrared observation window and connect them to the infrared data acquisition computer.

[0024] Step Six: Connect the gas tank to the air inlet at the front of the base plate via a pneumatic pipeline, open the gas tank valve, adjust the air inlet valve and exhaust port to supply a fixed X-axis gas pressure, and adjust the gas pressure to the required test pressure through the pressure data sensor connected via the pneumatic pipeline and the upper exhaust port; control the Z-axis and Y-axis loading systems of the rigid loading system to apply pressure to the Z-axis and Y-axis compression rods, so that the Z-axis and Y-axis compression rods extend into the gas confining chamber through the Z-axis and Y-axis pressure head channels;

[0025] Step 7: Start the test. The acoustic emission data acquisition computer, infrared data acquisition computer, pressure data acquisition computer, and LVTD data acquisition computer collect data simultaneously. The rigid loading system controls the pressure changes of the Z and Y direction compression rods.

[0026] Step 8: When rapidly unloading the confining pressure in the X direction, fully open the pressure relief valve on the rear pressure relief port, and the X-direction air pressure will be rapidly released within 0.1 seconds;

[0027] Step 9: After the test, the rigid loading system controls the depressurization in the Z and Y directions. After the depressurization is completed, the gas confining chamber is pushed out along the slide rail on the rigid loading system, the large bolt is unscrewed, the lifting ring is screwed into the threaded channel of the Z-direction extrusion rod, and the robotic arm is controlled to lift the top cover, the large bolt and the gas confining chamber.

[0028] Step 10: Press and hold the side button of the loading plate. At this time, the internal top column moves along the top column slide rail, pushes out the buckle, removes the loading frame, removes the acoustic emission probe, cleans the test platform, and after the test is completed, lower the top cover, large bolts and gas confinement chamber.

[0029] Furthermore, after the experiment was completed, the total heat exchange of the sample was calculated using a method for calculating the total heat exchange of the sample throughout the entire process:

[0030] In thermodynamics, based on the Stefan-Boltzmann law: J = ε × σ × T;

[0031] J: Radiance (total energy radiated per unit area per unit time), unit: watts per square meter (W / m²).

[0032] ε: Emissivity (radiative efficiency of an object). For a blackbody, ε = 1; for a real object, 0 < ε < 1.

[0033] σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4

[0034] T: Thermodynamic temperature (absolute temperature), unit: Kelvin (K).

[0035] Therefore, the formula for calculating the infrared heat exchange between the sample X and its front and rear surfaces per unit time is: IR(t) = A × ε × σ × T(t) 4 ×Δt

[0036] Where IR(t) is the infrared heat exchanged on the sample surface in the X direction per unit time.

[0037] A is the surface area of ​​the sample in the X direction.

[0038] ε: Emissivity (radiative efficiency of an object). For a blackbody, ε = 1; for a real object, 0 < ε < 1.

[0039] σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 .

[0040] T(t): The average thermodynamic temperature (absolute temperature) of the sample surface at time t, in Kelvin (K).

[0041] Δt is the unit time interval, in seconds;

[0042] Throughout the loading process, the Z-axis and Y-axis surfaces of the specimens were in contact with the loading plate 21. After the static period ended, the overall temperature of the specimens before the test was started was consistent with the overall system temperature, both being the initial temperatures monitored before the test. The overall system temperature can be considered infinitely large compared to the specimen temperature, meaning that the temperature change of the specimens has a negligible impact on the temperature change of the system. The overall temperature of the specimens can be approximated as the average of the average surface temperatures of the specimens from X to the front and back at time t0. Therefore, the formula for calculating the surface heat of the specimens in the Z-axis and Y-axis directions per unit time is: I(t) = ((Tx1(t) + Tx2(t)) / 2 - (Tx1(t0) + Tx2(t0)) / 2) / (L A / JA +L B / J B +1 / (A×hc))×A×Δt

[0043] Where I(t) is the heat exchanged between the sample and the loading plate contact surface per unit time.

[0044] L A The overall thickness of the specimen is shown, with the Z-axis representing the specimen height and the Y-axis representing the specimen width.

[0045] J A Thermal conductivity of the sample, in W / (m•K)

[0046] L B Loading plate thickness

[0047] J B Thermal conductivity of the loading plate, in W / (m•K)

[0048] hc: Contact thermal resistivity, unit W / (m) 2 •K)

[0049] Tx1(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction at time t before the initial time, in Kelvin (K).

[0050] Tx2(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction after the initial time at time t, in Kelvin (K).

[0051] Δt is the unit time interval, in seconds;

[0052] Therefore, the total amount of heat energy exchanged by the sample throughout the entire process is the sum of the heat radiation from the front and rear surfaces of the sample in the X direction and the heat conduction at the contact surfaces in the Z and Y directions. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iy(t)+2×∑Iz(t).

[0053] A method for a conventional triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring includes the following steps:

[0054] Step 1: Screw the lifting ring into the threaded channel of the top cover, and control the robotic arm to lower the hook to lift the top cover and the gas confining chamber;

[0055] Step 2: Connect the acoustic emission probe to the wires, and place the rubber pad and spring in sequence at the rear of the acoustic emission probe. Press the buckle and place the loading frame in the slot of the frame. After the loading frame fits, the front port of the acoustic emission probe is exposed. Insert a loading plate into the pressure head of the Z-axis extrusion rod, and connect the wires connected to the acoustic emission probe to the acoustic emission integrated interface of the base.

[0056] Step 3: Attach the strain gauge to the Y-axis surface of the specimen, install the prepared specimen onto another loading plate, place the whole specimen on the specimen stage, adjust the position, connect the strain gauge wire to the LVDT integrated interface, and connect the acoustic emission wire to the acoustic emission integrated interface;

[0057] Step 4: Control the robotic arm hook to lower the top cover and gas confining chamber, screw the large bolt into the threaded hole of the base plate, tighten it, and remove the lifting ring; place the gas confining chamber on the slide rail of the rigid loading system;

[0058] Step 5: Connect the acoustic emission data acquisition computer and the LVDT data acquisition computer. Set up infrared thermal imager I and infrared thermal imager II on both sides of the infrared observation window and connect them to the infrared data acquisition computer.

[0059] Step Six: Connect the gas tank to the air inlet at the front of the base plate via a pneumatic pipeline, open the gas tank valve, adjust the air inlet valve and exhaust port to supply a fixed X-axis gas pressure, and adjust the gas pressure to the required test pressure through the pressure data sensor connected via the pneumatic pipeline and the upper exhaust port; control the Z-axis and Y-axis loading systems of the rigid loading system to apply pressure to the Z-axis and Y-axis compression rods, so that the Z-axis and Y-axis compression rods extend into the gas confining chamber through the Z-axis and Y-axis pressure head channels;

[0060] Step 7: Start the test. The acoustic emission data acquisition computer, infrared data acquisition computer, pressure data acquisition computer, and LVTD data acquisition computer collect data simultaneously. The rigid loading system controls the pressure changes of the Z and Y direction compression rods.

[0061] Step 8: When rapidly unloading the confining pressure in the X direction, fully open the pressure relief valve connected to the rear pressure relief port, and the X-direction air pressure will be rapidly released within 0.1 seconds;

[0062] Step 9: After the test, the rigid loading system controls the Z-axis depressurization. After the depressurization is completed, the gas confining chamber is pushed out along the slide rail, the large bolt is unscrewed, the lifting ring is screwed into the threaded channel of the Z-axis extrusion rod, and the robotic arm is controlled to lift the top cover, the large bolt and the gas confining chamber.

[0063] Step 10: Press and hold the side button of the loading plate. At this time, the internal top column moves along the top column slide rail, pushes out the buckle, removes the loading frame, removes the acoustic emission probe, cleans the test platform, and after the test is completed, lower the top cover, large bolts and gas confinement chamber.

[0064] Furthermore, when using cylindrical specimens for conventional triaxial rapid unloading confining pressure tests, the X-axis infrared thermal imager can monitor the entire surface of the specimen's sidewalls, while the specimen remains in contact with the loading plate in the Z-axis direction. Therefore, the total heat exchange on the specimen surface throughout the entire process is the sum of the radiation energy from the specimen's sidewalls and the heat transfer energy in the Z-axis direction, calculated using the following formula:

[0065] Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t)

[0066] Where IRx1(t) and IRx2(t) represent the infrared heat exchange between the sample X and its front and rear surfaces per unit time, respectively, and are calculated using the formula: IR(t) = A × ε × σ × T(t) 4 ×Δt

[0067] A is the surface area of ​​the sample in the X direction.

[0068] ε: Emissivity (radiative efficiency of an object), ε=1 for a blackbody, 0<ε<1 for a real object;

[0069] σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 ;

[0070] T(t): The average thermodynamic temperature (absolute temperature) of the sample surface at time t, in Kelvin (K).

[0071] Δt is the unit time interval, in seconds;

[0072] The formula for calculating the heat on the sample surface in the Z direction per unit time is: I(t) = ((Tx1(t) + Tx2(t)) / 2 - (Tx1(t0) + Tx2(t0)) / 2) / (L A / J A +L B / J B +1 / (A×hc))×A×Δt

[0073] Where I(t) is the heat exchanged between the sample and the loading plate contact surface per unit time.

[0074] L A Z-axis sample height

[0075] J A Thermal conductivity of the sample, in W / (m•K)

[0076] L B Loading plate thickness

[0077] J B Thermal conductivity of the loading plate, in W / (m•K)

[0078] hc: Contact thermal resistivity, unit W / (m) 2 •K)

[0079] Tx1(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction at time t before the initial time, in Kelvin (K).

[0080] Tx2(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction after the initial time at time t, in Kelvin (K).

[0081] Δt is the unit time interval, in seconds.

[0082] Furthermore, when using a cubic specimen for a conventional triaxial rapid unloading confining pressure test, the specimen is in contact with the confining gas in the Y direction and cannot be monitored by an infrared monitoring system. The overall confining gas can be considered infinitely large, and the temperature of the confining gas is the same as the initial temperature of the specimen surface. Therefore, the formula for calculating the heat exchange of the specimen in the Y direction per unit time is:

[0083] Iy(t) = A × h gas ×(T(t)-T1)×Δt

[0084] Where Iy(t) is the surface heat of the sample in the Y direction at time t.

[0085] h gas Thermal conductivity of confining gas, in W / (m²•K).

[0086] T(t): The average thermodynamic temperature (absolute temperature) of the sample surface at time t, in Kelvin (K).

[0087] T1: Average thermodynamic temperature (absolute temperature) of the sample surface at the initial moment, unit: Kelvin (K).

[0088] Δt: unit time interval, unit s

[0089] Therefore, the total heat exchange on the sample surface throughout the entire process is the sum of the total heat radiation from X to the front and back, the total heat flow conduction to both sides in Y direction, and the total heat conduction at the contact surface in Z direction. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t)+2×Iy(t).

[0090] This invention provides a true triaxial rapid unloading confining pressure test system and method for rocks using infrared and acoustic emission monitoring. It achieves synchronous, real-time, and high-precision joint monitoring of the infrared thermal field evolution, acoustic emission activity, and circumferential axial strain throughout the entire rock failure process under true triaxial and conventional triaxial stress states. Furthermore, it innovatively proposes a quantitative calculation method for all infrared thermal energy during the entire sample failure process. This system can accurately capture the mechanical response of coal and rock samples under true triaxial and conventional triaxial loading and rapid unloading confining pressure monitoring, while simultaneously capturing transient temperature field anomalies and thermal energy release patterns throughout the entire process from micro-fracture to macro-instability. Combined with acoustic emission monitoring, it enables visualization of the initiation and propagation of micro-cracks within and on the surface of the coal and rock mass. In particular, it has made a breakthrough by establishing a method for calculating the infrared thermal energy throughout the entire process, transforming temperature distribution into quantifiable thermodynamic energy evolution data, providing direct evidence for revealing the force-thermal-acoustic coupling mechanism of coal and rock disasters. Compared to traditional equipment, this system not only expands the multi-parameter monitoring capabilities under conventional triaxial gas-solid coupling conditions, but also fills the gap in in-situ collaborative monitoring technology of multi-physics fields for coal and rock fractures induced by rapid unloading (simulating disasters such as rock bursts, water inrushes, and gas outbursts) under true triaxial gas-solid coupling, significantly improving the scientific accuracy of disaster early warning and rock mass stability evaluation in deep engineering. Attached Figure Description

[0091] Figure 1 This is a front view of the system of the present invention;

[0092] Figure 2 This is a system side view of the present invention;

[0093] Figure 3 This is a three-dimensional view of the system of the present invention;

[0094] Figure 4 This is a cross-sectional view of the gas-confined pressure chamber of the present invention;

[0095] Figure 5 This is a side sectional view of the gas-confined pressure chamber of the present invention;

[0096] Figure 6 This is a top sectional view of the gas-confined pressure chamber of the present invention;

[0097] Figure 7 This is a perspective view of the loading plate and card frame of the present invention;

[0098] Figure 8 This is a cross-sectional view of the loading plate and buckle of the present invention;

[0099] Figure 9 This is a schematic diagram of the lifting ring of the present invention.

[0100] In the diagram: 1-1-Z-direction extrusion rod; 1-2-Y-direction extrusion rod; 2-Top cover; 3-Exhaust port; 4-Infrared observation window; 5-Large bolt; 6-Side wall; 7-Acoustic emission integrated interface; 8-Base plate; 9-Acoustic emission signal channel; 10-1-Front air inlet; 10-2-Rear pressure relief port; 11-Sample stage; 12-Air inlet; 13-LVTD integrated interface; 14-Threaded hole; 15-LVTD signal channel; 16-Guide sleeve; 17-1-Z-direction pressure head channel O-ring seal; 17-2-Y-direction pressure head channel O-ring seal; 17-3-Bottom O-ring seal; 18-Lifting ring; 19-Air inlet channel; 20-Sample; 21-Loading plate; 22-Base; 23-Loading frame; 24-Snap fastener; 25-Spring; 26-Rubber gasket; 27-Acoustic emission probe; 28-Snap fastener channel; 29- Side button; 30 - Frame groove; 31 - Connecting knob; 32 - Gear; 33 - Lower hook; 34 - Top column; 35 - Engaging protrusion; 36 - Top column hook; 37 - Tension spring; 38 - Top column slide rail; 39 - Threaded channel; 40 - Gas confining chamber; 41 - Z-axis press frame; 42 - Z-axis cylinder; 43 - Z-axis servo pump; 44 - Pressure data acquisition computer; 45 - Y-axis press frame; 46 - Y-axis cylinder; 47 - Y-axis servo pump; 48 - Acoustic emission channel interface; 49 - LVTD Data channel; 50-Pneumatic pipeline; 51-Acoustic emission signal amplifier; 52-Acoustic emission data acquisition computer; 53-LVTD data acquisition computer; 54-Gas tank; 55-Pressure data sensor; 56-Pneumatic pressure data acquisition computer; 57-Hook; 58-Infrared thermal imager I; 59-Infrared thermal imager II; 60-Infrared data acquisition computer; 61-Inlet valve; 62-Pressure relief valve; 63-LVTD data transceiver; 64-Slide rail. Detailed Implementation

[0101] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0102] like Figures 1-9 As shown, a true triaxial rapid unloading confining pressure test system for rocks with infrared and acoustic emission monitoring includes a rigid loading system, a gas pressure control system, an infrared monitoring system, an acoustic emission data monitoring system, an LVTD monitoring system, and a gas confining pressure chamber 40.

[0103] The rigid loading system includes a Z-axis press frame 41, a Z-axis hydraulic cylinder 42, a Z-axis servo pump 43, a Y-axis press frame 45, a Y-axis hydraulic cylinder 46, a Y-axis servo pump 47, and a pressure data acquisition computer 44.

[0104] The air pressure control system includes an air pressure pipeline 50, a pressure data sensor 55, an air tank 54, an air inlet valve 61, a pressure relief valve 62, and an air pressure data acquisition computer 56.

[0105] The infrared monitoring system includes an infrared thermal imager I 58, an infrared thermal imager II 59, and an infrared data acquisition computer 60;

[0106] The LVTD monitoring system includes an LVTD data transceiver 63 and an LVTD data acquisition computer 53;

[0107] The acoustic emission data monitoring system includes an acoustic emission probe module, an acoustic emission signal amplifier 51, and an acoustic emission data acquisition computer 52.

[0108] The gas confined pressure chamber 40 includes a top cover 2, side walls 6, and a bottom plate 8. The top cover 2 has a Z-direction pressure head channel penetrating the inside and outside of the gas confined pressure chamber 40. A Z-direction extrusion rod 1-1 with a pressure head at its front end is movably installed within the Z-direction pressure head channel. Infrared observation windows 4 (made of CaF2 glass) are installed on the X-direction side walls, and a Y-direction pressure head channel is opened on the Y-direction side walls. A Y-direction extrusion rod 1-2 with a pressure head is movably installed within the Y-direction pressure head channel. Sealing elements are installed in both the Y-direction and Z-direction pressure head channels. The bottom plate 8 has a sample stage 11, an acoustic emission integrated interface 7, and an LVTD integrated interface 13 on its upper part. The base plate 8 has an air inlet channel 19, an LVTD signal channel 15, and an acoustic emission signal channel 9 inside. An air inlet 12 communicating with the air inlet channel 19 is located on the top of the base plate 8. A threaded channel 39 is located on the top of the Z-direction extrusion rod 1-1. A screw-in hook can be used to lift the top cover 2 and the gas confining chamber 40 connected to it. The Z-direction extrusion head channel has a Z-direction extrusion head channel O-ring 17-1, and the Y-direction extrusion head channel has a Y-direction extrusion head channel O-ring 17-2. A bottom O-ring 17-3 is located on the base plate to seal the gas confining chamber 40 when the extrusion head is loaded. An exhaust port 3 communicating with the inside and outside of the gas confining chamber 40 is located on the top center of the base plate 8. A base 22 is located on the upper center of the base plate 8, and the sample stage 11, acoustic emission integrated interface 7, and LVTD integrated interface 13 are all located on the base 22.

[0109] The top cover 2 and the bottom plate 8 are connected by large bolts 5, and the side plate 6 is sealed between the top cover 2 and the bottom plate 8. The large bolts 5 pass through the top cover 2 and can be inserted into the threaded hole 14 of the bottom plate. After tightening, the gas confining chamber 40 is sealed. The rear pressure relief port 10-2 of the air inlet channel 19 is connected to the gas tank 54 through the air pressure pipeline 50 to provide X-direction air pressure. The front air inlet 10-1 of the air inlet channel 19 is connected to the pressure data sensor 55, which is connected to the air pressure data acquisition computer 56 for real-time monitoring of the air pressure inside the gas confining chamber 40. The acoustic emission signal channel 9 is connected to the acoustic emission data acquisition computer 52 through the acoustic emission signal amplifier 51, and the LVTD signal channel 15 is connected to the LVTD data acquisition computer 53, which can realize real-time monitoring of acoustic emission, infrared, and pressure data during loading. The wires inside the acoustic emission signal channel 9 and the LVTD signal channel 15 are all wrapped with insulating varnish, and the channels are sealed by filling with sealant.

[0110] The acoustic emission probe module is connected to the acoustic emission signal channel 9. In the X-axis, gas pressure is supplied from an external gas source through the inlet channel. Loading in the Z and Y axes can be controlled by a rigid pressure loading system to achieve unconventional path loading such as cyclic loading and unloading.

[0111] Furthermore, the acoustic emission probe module includes a loading plate 21, an acoustic emission probe 27, and a pair of loading frames 23. The loading plate 21 has a pair of vertically arranged frame grooves 30 at its rear. Each frame groove 30 can house an acoustic emission probe 27, which is positioned by the loading frames 23. The loading frames 23 corresponding to the upper frame groove 30 have spring-supported buckles 24 at their lower ends, and the loading frames 23 corresponding to the lower frame groove have spring-supported buckles 24 at their upper ends. The upper frame groove 30 has a buckle channel 28 on its bottom surface, and the lower frame groove 30 has a buckle channel 28 on its top surface. When the acoustic emission probe 27 is connected to the loading frame 23, a rubber pad 26 and a spring 25 are sequentially arranged from the acoustic emission probe 27 end to the rear of the loading frame 23. The frame grooves 30 can embed the loading frame 23, and the loading frame 23 is fixed by embedding the buckles 24 into the buckle channels 28.

[0112] The loading plate 21 has a pair of side buttons 29 on both sides, corresponding to four latching channels 28 respectively. The loading plate 21 has a cavity inside, and gears 32 corresponding to the side buttons 29 are rotatably installed in the cavity. Each latching channel 28 has a top column slide rail 38 installed along the channel direction on its inner wall. A top column 34 is slidably installed on the top column slide rail 38. One side of the top column 34 has a meshing protrusion 35 that meshes with the gear 32. The bottom of the top column 34 is connected to a tension spring 37 through a top column hook 36. The other end of the tension spring 37 is connected to the bottom of the latching channel 28. The side buttons 29 and gears 32 are connected by hinges. Due to the action of the tension spring 37, the top post 34 is normally in a retracted state. When the side button 29 is pressed, the side button 29 drives the gear to rotate a certain angle through the hinge. The gear pushes the top post 34 up through the meshing protrusion 35. The top post 34 pushes out the buckle 24 in the buckle channel 28, and the loading plate 21 and the loading frame 23 are disconnected. Releasing the side button 29 causes the top post 34 to retract under the action of the tension spring 37. The loading plate 21 has a groove between the upper and lower frame grooves for fixing the sample. At the same time, different loading plates can be connected by interlocking their edges. The interlocking structure can be achieved through various existing technologies such as slots and tenon joints. The other end of the loading plate without the groove is used to contact the extrusion rod head.

[0113] A guide sleeve 16 is also provided between the extrusion rod and the pressure head channel to ensure the stability of the extrusion rod in the axial direction and to prevent the extrusion rod from leaving the pressure head channel. When the gas confining chamber 40 is lifted by the lifting ring 18, it can also prevent the Z-axis extrusion rod from leaving the gas confining chamber 40.

[0114] A rapid triaxial unloading confining pressure test method for rocks using infrared and acoustic emission monitoring includes the following steps:

[0115] Step 1: Screw the lifting ring 18 into the threaded channel 39 of the top cover 2, control the robotic arm to lower the hook 57, and lift the top cover 2 and the gas confining chamber 40;

[0116] Step 2: Connect the acoustic emission probe 27 to the wires. Place the rubber pad 26 and spring 25 in sequence at the rear of the acoustic emission probe 27. Press the buckle 24 and place the loading frame 23 in the frame groove 30. After the loading frame 23 fits with the loading plate 21, the front port of the acoustic emission probe 27 is exposed. Insert one Z-direction loading plate 21 and two Y-direction loading plates 21 into the pressure heads of the Z-direction compression rod 1-1 and the Y-direction compression rod 1-2 respectively. Connect the wires connected to the acoustic emission probe 27 to the acoustic emission integrated interface 7 of the base 22.

[0117] Step 3: Attach the strain gauge to the Y-axis surface of the specimen 20, install the prepared specimen onto another Z-axis loading plate 21, place the whole specimen on the specimen stage 11, adjust the position, and engage the loading plates 21 on the pressure heads of the Z-axis compression rod 1-1 and the Y-axis compression rod 1-2 with the loading plates on the specimen stage 11 (the loading plates can engage with each other to surround the Z and Y axes of the specimen, while exposing the X axis), and connect the strain gauge wires to the LVDT integrated interface 13;

[0118] Step 4: Control the robotic arm to lower the top cover 2 and the gas confining chamber 40, screw the large bolt 5 into the bolt hole of the base plate 8, tighten it, and let it stand still on the slide rail 64 of the rigid loading system until the sample 20 and the confining gas adsorption reach equilibrium and the temperature is the same as the overall system temperature.

[0119] Step 5: Connect the acoustic emission data acquisition computer 52 and the LVDT data acquisition computer 53. Set up the infrared thermal imager I58 and the infrared thermal imager II59 on both sides of the infrared observation window 4 and connect them to the infrared data acquisition computer 60.

[0120] Step Six: Connect the gas tank 54 to the front air inlet 10-1 of the base plate 8 through the air pressure pipeline 50, open the gas tank valve, adjust the air inlet valve 61 and the exhaust port 3 to supply a fixed X-axis gas pressure, and adjust the gas pressure to the required test pressure through the pressure data sensor 55 connected to the air pressure pipeline 50 and the upper exhaust port 3; control the Z-axis and Y-axis loading systems of the rigid loading system to apply pressure to the Z-axis and Y-axis compression rods, so that the Z-axis and Y-axis compression rods extend into the gas confining chamber 40 through the Z-axis and Y-axis pressure head channels;

[0121] Step 7: Start the test. Acoustic emission data acquisition computer 52, infrared data acquisition computer 60, pressure data acquisition computer 44, and LVTD data acquisition computer 53 simultaneously acquire data. The rigid loading system controls the pressure changes of the Z and Y direction extrusion rods.

[0122] Step 8: When rapidly unloading the confining pressure in the X direction, fully open the pressure relief valve 62 on the rear pressure relief port 10-2, and the X-direction air pressure will be rapidly released within 0.1 seconds;

[0123] Step 9: After the test, the rigid loading system controls the Z and Y directions to depressurize. After the depressurization is completed, the gas confining chamber 40 is pushed out along the slide rail 64 on the rigid loading system, the large bolt 5 is unscrewed, the lifting ring 18 is screwed into the threaded channel 39 of the Z-direction extrusion rod 1-1, and the robotic arm is controlled to lift the top cover 2, the large bolt 5 and the gas confining chamber 40.

[0124] Step 10: Press and hold the side button 29 on the loading plate. At this time, the internal top column 34 moves along the top column slide rail 38, pushes out the buckle 24, remove the loading frame 23, remove the acoustic emission probe 27, clean the test platform, and after the test is completed, put down the top cover 2, the large bolt 5 and the gas confining chamber 40.

[0125] Furthermore, after the experiment was completed, the total heat exchange of the sample was calculated using a method for calculating the total heat exchange of the sample throughout the entire process:

[0126] In thermodynamics, based on the Stefan-Boltzmann law: J = ε × σ × T;

[0127] J: Radiance (total energy radiated per unit area per unit time), unit: watts per square meter (W / m²).

[0128] ε: Emissivity (radiative efficiency of an object). For a blackbody, ε = 1; for a real object, 0 < ε < 1.

[0129] σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4

[0130] T: Thermodynamic temperature (absolute temperature), unit: Kelvin (K).

[0131] Therefore, the formula for calculating the infrared heat exchange between the sample X and its front and rear surfaces per unit time is: IR(t) = A × ε × σ × T(t) 4 ×Δt

[0132] Where IR(t) is the infrared heat exchanged on the sample surface in the X direction per unit time.

[0133] A is the surface area of ​​the sample in the X direction.

[0134] ε: Emissivity (radiative efficiency of an object). For a blackbody, ε = 1; for a real object, 0 < ε < 1.

[0135] σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 .

[0136] T(t): The average thermodynamic temperature (absolute temperature) of the sample surface at time t, in Kelvin (K).

[0137] Δt is the unit time interval, in seconds;

[0138] Throughout the loading process, the Z-axis and Y-axis surfaces of the specimens were in contact with the loading plate 21. After the static period ended, the overall temperature of the specimens before the test was started was consistent with the overall system temperature, both being the initial temperatures monitored before the test. The overall system temperature can be considered infinitely large compared to the specimen temperature, meaning that the temperature change of the specimens has a negligible impact on the temperature change of the system. The overall temperature of the specimens can be approximated as the average of the average surface temperatures of the specimens from X to the front and back at time t0. Therefore, the formula for calculating the surface heat of the specimens in the Z-axis and Y-axis directions per unit time is: I(t) = ((Tx1(t) + Tx2(t)) / 2 - (Tx1(t0) + Tx2(t0)) / 2) / (L A / J A +L B / J B +1 / (A×hc))×A×Δt

[0139] Where I(t) is the heat exchanged between the sample and the loading plate contact surface per unit time.

[0140] L A The overall thickness of the specimen is shown, with the Z-axis representing the specimen height and the Y-axis representing the specimen width.

[0141] J A Thermal conductivity of the sample, in W / (m•K)

[0142] L B Loading plate thickness

[0143] J B Thermal conductivity of the loading plate, in W / (m•K)

[0144] hc: Contact thermal resistivity, unit W / (m) 2 •K)

[0145] Tx1(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction at time t before the initial time, in Kelvin (K).

[0146] Tx2(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction after the initial time at time t, in Kelvin (K).

[0147] Δt is the unit time interval, in seconds;

[0148] Therefore, the total amount of heat energy exchanged by the sample throughout the entire process is the sum of the heat radiation from the front and rear surfaces of the sample in the X direction and the heat conduction at the contact surfaces in the Z and Y directions. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iy(t)+2×∑Iz(t).

[0149] A method for a conventional triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring includes the following steps:

[0150] Step 1: Screw the lifting ring 18 into the threaded channel 39 of the top cover 2, and control the robotic arm to lower the hook 57 to lift the top cover 2 and the gas confining chamber 40.

[0151] Step 2: Connect the acoustic emission probe 27 to the wires, and place the rubber pad 26 and spring 25 in sequence at the rear of the acoustic emission probe 27. Hold down the buckle 24 and place the loading frame 23 in the frame groove 30. After the loading frame 23 is engaged, the front port of the acoustic emission probe 27 is exposed. Insert a loading plate 21 into the pressure head of the Z-direction extrusion rod 1-1, and connect the wires connected to the acoustic emission probe 27 to the acoustic emission integrated interface 7 of the base 22.

[0152] Step 3: Adhere the strain gauge to the Y-axis surface of the specimen, install the prepared specimen 20 onto another loading plate 23, place the whole specimen on the specimen stage 11, adjust the position (equivalent to the Z-axis of the specimen, i.e., the upper and lower surfaces, contacting the loading plate), connect the strain gauge wire to the LVDT integrated interface 13, and connect the acoustic emission wire to the acoustic emission integrated interface 7.

[0153] Step 4: Control the robotic arm hook 57 to lower the top cover 2 and the gas confining chamber 40, screw the large bolt 5 into the threaded hole 14 of the base plate, tighten it, and remove the lifting ring 18; place the gas confining chamber 40 on the slide rail 64 of the rigid loading system;

[0154] Step 5: Connect the acoustic emission data acquisition computer 52 and the LVDT data acquisition computer 53. Set up the infrared thermal imager I58 and the infrared thermal imager II59 on both sides of the infrared observation window 4 and connect them to the infrared data acquisition computer 60.

[0155] Step Six: Connect the gas tank 54 to the front air inlet 10-1 of the base plate 8 through the air pressure pipeline 50, open the gas tank valve, adjust the air inlet valve 61 and the exhaust port 3 to supply a fixed X-axis gas pressure, and adjust the gas pressure to the required test pressure through the pressure data sensor 55 connected to the air pressure pipeline 50 and the upper exhaust port 3; control the Z-axis and Y-axis loading systems of the rigid loading system to apply pressure to the Z-axis and Y-axis compression rods, so that the Z-axis and Y-axis compression rods extend into the gas confining chamber 40 through the Z-axis and Y-axis pressure head channels;

[0156] Step 7: Start the test. Acoustic emission data acquisition computer 52, infrared data acquisition computer 60, pressure data acquisition computer 44, and LVTD data acquisition computer 53 simultaneously acquire data. The rigid loading system controls the pressure changes of the Z and Y direction extrusion rods.

[0157] Step 8: When rapidly unloading the confining pressure in the X direction, fully open the pressure relief valve 62 connected to the rear pressure relief port 10-2, and the X-direction air pressure will be rapidly released within 0.1 seconds;

[0158] Step 9: After the test, the rigid loading system controls the Z-axis depressurization. After the depressurization is completed, the gas confining chamber 40 is pushed out along the slide rail 64, the large bolt 5 is unscrewed, the lifting ring 18 is screwed into the threaded channel 39 of the Z-axis extrusion rod 1-1, and the robotic arm is controlled to lift the top cover 2, the large bolt 5 and the gas confining chamber 40.

[0159] Step 10: Press and hold the side button 29 on the loading plate 21. At this time, the internal top column 34 moves along the top column slide rail 38, pushes out the buckle 24, remove the loading frame 23, remove the acoustic emission probe 27, clean the test platform, and after the test is completed, put down the top cover 2, the large bolt 5 and the gas confining chamber 40.

[0160] Furthermore, when using cylindrical specimens for conventional triaxial rapid unloading confining pressure tests, the X-axis infrared thermal imager can monitor the entire surface of the specimen's sidewalls, while the specimen remains in contact with the loading plate in the Z-axis direction. Therefore, the total heat exchange on the specimen surface throughout the entire process is the sum of the radiation energy from the specimen's sidewalls and the heat transfer energy in the Z-axis direction, calculated using the following formula:

[0161] Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t).

[0162] Furthermore, when using a cubic specimen for a conventional triaxial rapid unloading confining pressure test, the specimen is in contact with the confining gas in the Y direction and cannot be monitored by an infrared monitoring system. The overall confining gas can be considered infinitely large, and the temperature of the confining gas is the same as the initial temperature of the specimen surface. Therefore, the formula for calculating the heat exchange of the specimen in the Y direction per unit time is:

[0163] Iy(t) = A × h gas ×(T(t)-T1)×Δt

[0164] Where Iy(t) is the surface heat of the sample in the Y direction at time t.

[0165] h gas Thermal conductivity of confining gas, in W / (m²•K).

[0166] T(t): The average thermodynamic temperature (absolute temperature) of the sample surface at time t, in Kelvin (K).

[0167] T1: Average thermodynamic temperature (absolute temperature) of the sample surface at the initial moment, unit: Kelvin (K).

[0168] Δt: unit time interval, unit s

[0169] Therefore, the total heat exchange on the sample surface throughout the entire process is the sum of the total heat radiation from X to the front and back, the total heat flow conduction to both sides in Y direction, and the total heat conduction at the contact surface in Z direction. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t)+2×Iy(t).

Claims

1. A rock true triaxial rapid unloading confining pressure test system with infrared and acoustic emission monitoring, comprising a rigid loading system, a gas pressure control system, an infrared monitoring system, an acoustic emission data monitoring system, an LVTD monitoring system, and a gas confining pressure chamber (40). The rigid loading system includes a Z-axis press frame (41), a Z-axis loading system, a Y-axis press frame (45), a Y-axis loading system, and a pressure data acquisition computer (44). The air pressure control system includes an air pressure pipeline (50), a pressure data sensor (55), an air tank (54), an air inlet valve (61), a pressure relief valve (62), and an air pressure data acquisition computer (56). The infrared monitoring system includes an infrared thermal imager I (58), an infrared thermal imager II (59), and an infrared data acquisition computer (60). The LVTD monitoring system includes an LVTD data transmitter (63) and an LVTD data acquisition computer (53). The acoustic emission data monitoring system includes an acoustic emission probe module and an acoustic emission data acquisition computer (52). The gas confined pressure chamber (40) includes a top cover (2), side walls (6), and a bottom plate (8); the top cover (2) is provided with a Z-direction pressure head channel that runs through the inside and outside of the gas confined pressure chamber (40), and a Z-direction extrusion rod (1-1) with a pressure head at the front end is movably installed in the Z-direction pressure head channel; infrared observation windows (4) are installed on the X-direction side walls, and a Y-direction pressure head channel is opened on the Y-direction side walls, and a Y-direction extrusion rod (1-2) with a pressure head is movably installed in the Y-direction pressure head channel; both the Y-direction and Z-direction pressure head channels are equipped with sealing elements; The base plate (8) is provided with a sample stage (11), an acoustic emission integrated interface (7), and an LVTD integrated interface (13) on its upper part. The base plate (8) is provided with an air inlet channel (19), an LVTD signal channel (15), and an acoustic emission signal channel (9) inside. The top of the base plate (8) has an air inlet (12) that communicates with the air inlet channel (19). The top of the Z-direction extrusion rod (1-1) is provided with a threaded channel (39). The top cover (2) is provided with an exhaust port (3) that communicates with the inside and outside of the gas confining chamber (6). The top cover (2) and the bottom plate (8) are connected by large bolts (5), and the side plate (6) is sealed between the top cover (2) and the bottom plate (8); the rear pressure relief port (10-2) of the air inlet channel (19) is connected to the gas tank (54) through the air pressure pipeline (50) to provide X-direction air pressure; the front air inlet (10-1) of the air inlet channel (19) is connected to the pressure data sensor (55), and the pressure data sensor (55) is connected to the air pressure data acquisition computer (56) to monitor the internal air pressure of the gas confining chamber (6) in real time; the acoustic emission signal channel (9) is connected to the acoustic emission data acquisition computer (52), and the LVTD signal channel (15) is connected to the LVTD data acquisition computer (53), which can realize real-time monitoring of acoustic emission, infrared and pressure data during loading; The acoustic emission probe module is connected to the acoustic emission signal channel (9).

2. The true triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring as described in claim 1, characterized in that, The acoustic emission probe module includes a loading plate (21), an acoustic emission probe (27), and a pair of loading frames (23); the loading plate (21) has a pair of vertically arranged frame grooves (30) at the rear, each frame groove (30) can house an acoustic emission probe (27) and the acoustic emission probe (27) is positioned by the loading frames (23); the loading frames (23) corresponding to the upper frame groove (30) have spring-supported buckles (24) at the lower ends, and the loading frames (23) corresponding to the lower frame groove have spring-supported buckles (24) at the upper ends. The part is provided with a buckle (24) supported by a spring; the bottom surface of the upper frame groove (30) is provided with a buckle channel (28), and the top surface of the lower frame groove (30) is provided with a buckle channel (28); when the acoustic emission probe (27) is connected to the loading frame (23), a rubber pad (26) and a spring (25) are arranged sequentially from the end of the acoustic emission probe (27) to the rear of the loading frame (23); the frame groove (30) can embed the loading frame (23), and the loading frame (23) is fixed by embedding the buckle (24) into the buckle channel (28); A pair of side buttons (29) are provided on both sides of the loading plate (21), corresponding to four buckle channels (28) respectively; the loading plate (21) has a cavity inside, and gears (32) corresponding to the side buttons (29) are rotatably installed in the cavity; a top column slide rail (38) is installed on the inner wall of each buckle channel (28) along the channel direction; a top column (34) is slidably installed on the top column slide rail (38); a meshing protrusion (35) that meshes with the gear (32) is provided on one side of the top column (34); a tension spring (37) is connected to the bottom of the top column (34) through the top column hook (36); the other end of the tension spring (37) is connected to the bottom of the buckle channel (28); the side buttons (29) and the gears (32) are connected by a hinge; The base plate (8) has a base (22) at the center of the upper part, and the sample stage (11), acoustic emission integrated interface (7), and LVTD integrated interface (13) are all located on the base (22).

3. A method for rapid triaxial unloading confining pressure testing of rock using infrared and acoustic emission monitoring, implemented using the rapid triaxial unloading confining pressure testing system for rock using infrared and acoustic emission monitoring as described in claim 2, characterized in that... Includes the following steps: Step 1: Screw the lifting ring (18) into the threaded channel (39) of the top cover (2), and control the robotic arm to lower the hook (57) to lift the top cover 2 and the gas confining chamber (40); Step 2: Connect the acoustic emission probe (27) to the wires. Set the rubber pad 26 and spring (25) in sequence at the rear of the acoustic emission probe (27). Press the buckle (24) and place the loading frame (23) in the slot (30). After the loading frame (23) fits with the loading plate (21), the front port of the acoustic emission probe (27) is exposed. Insert one Z-direction loading plate (21) and two Y-direction loading plates (21) into the pressure heads of the Z-direction compression rod (1-1) and the Y-direction compression rod (1-2) respectively. Connect the wires connected to the acoustic emission probe (27) to the acoustic emission integrated interface (7) of the base (22). Step 3: Adhere the strain gauge to the Y-direction surface of the specimen (20), install the prepared specimen onto another Z-direction loading plate (21), place the whole specimen on the specimen stage (11), adjust the position, and fasten the loading plate (21) on the pressure head of the Z-direction extrusion rod (1-1) and the Y-direction extrusion rod (1-2) to the loading plate on the specimen stage (11). Connect the strain gauge wire to the LVDT integrated interface (13). Step 4: Control the robotic arm to lower the top cover (2) and the gas confining chamber (40), screw the large bolt (5) into the bolt hole of the base plate (8), tighten it, and let it stand on the slide rail (64) of the rigid loading system until the sample (20) reaches equilibrium with the confining gas and the temperature is the same as the overall system temperature. Step 5: Connect the acoustic emission data acquisition computer (52) and the LVDT data acquisition computer (53), set up the infrared thermal imager I (58) and the infrared thermal imager II (59) on both sides of the infrared observation window 4, and connect them to the infrared data acquisition computer (60). Step 6: Connect the gas tank (54) to the front air inlet (10-1) of the base plate (8) through the air pressure pipeline (50), open the gas tank valve, adjust the air inlet valve (61) and exhaust port (3) to supply a fixed X-direction gas pressure, and adjust the gas pressure required for the test through the pressure data sensor (55) connected through the air pressure pipeline (50) and the upper exhaust port (3); control the Z-direction and Y-direction loading systems of the rigid loading system to apply pressure to the Z-direction and Y-direction extrusion rods, so that the Z-direction and Y-direction extrusion rods extend into the gas confining chamber (40) through the Z-direction and Y-direction pressure head channels; Step 7: Start the test. Acoustic emission data acquisition computer (52), infrared data acquisition computer (60), pressure data acquisition computer (44), and LVTD data acquisition computer (53) collect data synchronously. The rigid loading system controls the pressure changes of the Z-axis and Y-axis compression rods. Step 8: When rapidly unloading the confining pressure in the X direction, fully open the pressure relief valve (62) on the rear pressure relief port (10-2), and the X-direction air pressure will be rapidly released within 0.1s; Step 9: After the test, the rigid loading system controls the Z and Y directions to depressurize. After the depressurization is completed, the gas confining chamber (40) is pushed out along the slide rail (64) on the rigid loading system, the large bolt (5) is unscrewed, the lifting ring (18) is screwed into the threaded channel (39) of the Z-direction extrusion rod (1-1), and the robotic arm is controlled to lift the top cover (2), the large bolt (5) and the gas confining chamber (40); Step 10: Press and hold the side button (29) of the loading plate. At this time, the internal top column (34) moves along the top column slide rail (38), pushes out the buckle (24), takes out the loading frame (23), takes out the acoustic emission probe (27), cleans the test platform, and after the test, put down the top cover (2), the large bolt (5) and the gas confining chamber (40).

4. The method for rapid unloading of confining pressure in true triaxial rock testing with infrared and acoustic emission monitoring as described in claim 3, characterized in that, After the experiment, the total heat exchange of the sample was calculated using a method for calculating the total heat exchange of the sample throughout the entire process. Thermodynamically, based on the Stefan-Boltzmann law: J = ε × σ × T; J: Radiance, unit: watts per square meter (W / m²) ε: Emissivity; for a blackbody, ε=1; for a real object, 0<ε<1. σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 T: Thermodynamic temperature, unit: Kelvin (K) Therefore, the formula for calculating the infrared heat exchange between the sample X and its front and rear surfaces per unit time is: IR(t) = A × ε × σ × T(t) 4 ×Δt Where IR(t) is the infrared heat exchanged on the sample surface in the X direction per unit time. A is the surface area of ​​the sample in the X direction. ε: Emissivity; for a blackbody, ε=1; for a real object, 0<ε<1. σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 T(t): The average thermodynamic temperature of the sample surface at time t, in Kelvin (K). Δt is the unit time interval, in seconds; Throughout the loading process, the Z-axis and Y-axis surfaces of the specimens were in contact with the loading plate (21). After the static period ended, the overall temperature of the specimens before the test was started was consistent with the overall system temperature, both being the initial temperatures monitored before the test. The overall system temperature was considered to be infinitely large compared to the specimen temperature, meaning that the temperature change of the specimens had a negligible impact on the temperature change of the system. The overall temperature of the specimens could be approximated as the average of the average surface temperatures of the specimens from X to the back at time t0. Therefore, the formula for calculating the heat on the surface of the specimens in the Z-axis and Y-axis per unit time is: I(t) = ((Tx1(t) + Tx2(t)) / 2 - (Tx1(t0) + Tx2(t0)) / 2) / (L A / J A +L B / J B +1 / (A×hc))×A×Δt Where I(t) is the heat exchanged between the sample and the loading plate contact surface per unit time. L A The overall thickness of the specimen, the Z-axis represents the specimen height, and the Y-axis represents the specimen width. J A Thermal conductivity of the sample, in W / (m•K) L B Loading plate thickness J B Thermal conductivity of the loading plate, in W / (m•K) hc: Contact thermal resistivity, unit W / (m) 2 •K) Tx1(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction at time t before the initial time, in Kelvin (K). Tx2(t0): The average thermodynamic temperature (absolute temperature) of the sample surface in the X direction after the initial time at time t, in Kelvin (K). Δt is the unit time interval, in seconds; Therefore, the total amount of heat energy exchanged by the sample throughout the entire process is the sum of the heat radiation from the front and rear surfaces of the sample in the X direction and the heat conduction at the contact surfaces in the Z and Y directions. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iy(t)+2×∑Iz(t).

5. A method for a conventional triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring, implemented using the true triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring as described in claim 2, characterized in that... Includes the following steps: Step 1: Screw the lifting ring (18) into the threaded channel (39) of the top cover (2), and control the robotic arm to lower the hook (57) to lift the top cover (2) and the gas confining chamber (40); Step 2: Connect the acoustic emission probe (27) to the wires, and set the rubber pad (26) and spring (25) in sequence at the rear of the acoustic emission probe (27). Press the buckle (24) and place the loading frame (23) in the slot (30) of the frame. After the loading frame (23) fits, the front port of the acoustic emission probe (27) is exposed. Insert a loading plate (21) into the pressure head of the Z-direction extrusion rod (1-1) and connect the wires connected to the acoustic emission probe (27) to the acoustic emission integrated interface (7) of the base (22). Step 3: Adhere the strain gauge to the Y-direction surface of the specimen, install the prepared specimen (20) onto another loading plate (23), place the whole specimen on the specimen stage (11), adjust the position, connect the strain gauge wire to the LVDT integrated interface (13), and connect the acoustic emission wire to the acoustic emission integrated interface (7); Step 4: Control the robotic arm hook (57) to lower the top cover (2) and the gas confining chamber (40), screw the large bolt (5) into the threaded hole (14) of the base plate, tighten it, and remove the lifting ring (18); place the gas confining chamber (40) on the slide rail (64) of the rigid loading system; Step 5: Connect the acoustic emission data acquisition computer (52) and the LVDT data acquisition computer (53), set up the infrared thermal imager I (58) and the infrared thermal imager II (59) on both sides of the infrared observation window 4, and connect them to the infrared data acquisition computer (60). Step 6: Connect the gas tank (54) to the front air inlet (10-1) of the base plate (8) through the air pressure pipeline (50), open the gas tank valve, adjust the air inlet valve (61) and exhaust port (3) to supply a fixed X-direction gas pressure, and adjust the gas pressure required for the test through the pressure data sensor (55) connected through the air pressure pipeline (50) and the upper exhaust port (3); control the Z-direction and Y-direction loading systems of the rigid loading system to apply pressure to the Z-direction and Y-direction extrusion rods, so that the Z-direction and Y-direction extrusion rods extend into the gas confining chamber (40) through the Z-direction and Y-direction pressure head channels; Step 7: Start the test. Acoustic emission data acquisition computer (52), infrared data acquisition computer (60), pressure data acquisition computer (44), and LVTD data acquisition computer (53) collect data synchronously. The rigid loading system controls the pressure changes of the Z-axis and Y-axis compression rods. Step 8: When the X-direction confining pressure is rapidly unloaded, fully open the pressure relief valve (62) connected to the rear pressure relief port (10-2), and the X-direction air pressure will be rapidly unloaded within 0.1s; Step 9: After the test, the rigid loading system controls the Z-direction depressurization. After the depressurization is completed, the gas confining chamber (40) is pushed out along the slide rail (64), the large bolt (5) is unscrewed, the lifting ring (18) is screwed into the threaded channel (39) of the Z-direction extrusion rod (1-1), and the robotic arm is controlled to lift the top cover (2), the large bolt (5) and the gas confining chamber (40); Step 10: Press and hold the side button (29) of the loading plate (21). At this time, the internal top column (34) moves along the top column slide rail (38), pushes out the buckle (24), takes out the loading frame (23), takes out the acoustic emission probe (27), cleans the test platform, and after the test, put down the top cover (2), the large bolt (5) and the gas confining chamber (40).

6. The method for a conventional triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring as described in claim 5, characterized in that, When performing a conventional triaxial rapid unloading confining pressure test using a cylindrical specimen, the X-axis infrared thermal imager can monitor the entire surface of the specimen's sidewalls. The specimen remains in contact with the loading plate in the Z-axis direction. Therefore, the total heat exchange on the specimen surface throughout the entire process is the sum of the radiant energy from the specimen's sidewalls and the heat transfer energy in the Z-axis direction. The calculation formula is as follows: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t) Wherein, IRx1(t) and IRx2(t) represent the infrared heat exchange between the sample X and its front and rear surfaces per unit time, respectively, and are calculated using the formula: IR(t) = A × ε × σ × T(t) 4 ×Δt A is the surface area of ​​the sample in the X direction. ε: Emissivity; for a blackbody, ε=1; for a real object, 0<ε<1. σ: Stefan-Boltzmann constant σ≈5.670374419×10 -8 W•m -2 •K -4 ; T(t): The average thermodynamic temperature of the sample surface at time t, in Kelvin (K). Δt is the unit time interval, in seconds; The formula for calculating the heat on the sample surface in the Z direction per unit time is: I(t) = ((Tx1(t) + Tx2(t)) / 2 - (Tx1(t0) + Tx2(t0)) / 2) / (L A / J A +L B / J B +1 / (A×hc))×A×Δt Where I(t) is the heat exchanged between the sample and the loading plate contact surface per unit time. L A Z-axis sample height J A Thermal conductivity of the sample, in W / (m•K) L B Loading plate thickness J B Thermal conductivity of the loading plate, in W / (m•K) hc: Contact thermal resistivity, unit W / (m) 2 •K) Tx1(t0): The average thermodynamic temperature of the sample surface in the X direction before the initial time at time t, in Kelvin (K). Tx2(t0): The average thermodynamic temperature of the sample surface in the X direction after the initial time at time t, in Kelvin (K). Δt is the unit time interval, in seconds.

7. The method for a conventional triaxial rapid unloading confining pressure test system for rocks using infrared and acoustic emission monitoring according to claim 6, characterized in that, When performing a conventional triaxial rapid unloading confining pressure test using a cubic specimen, the specimen is in contact with the confining gas in the Y direction and cannot be monitored by an infrared monitoring system. The entire confining gas can be considered infinitely large, and the temperature of the confining gas is the same as the initial temperature of the specimen surface. Therefore, the formula for calculating the heat exchange of the specimen in the Y direction per unit time is: Iy(t)=A×h gas ×(T(t)-T1)×Δt Where Iy(t) is the surface heat of the sample in the Y direction at time t. h gas Thermal conductivity of confining gas, in W / (m²•K). T(t): The average thermodynamic temperature of the sample surface at time t, in Kelvin (K). T1: Average thermodynamic temperature of the sample surface at the initial moment, unit: Kelvin (K). Δt: unit time interval, unit is seconds; Therefore, the total heat exchange on the sample surface throughout the entire process is the sum of the total heat radiation from X to the front and back, the total heat flow conduction to both sides in Y direction, and the total heat conduction at the contact surface in Z direction. The calculation formula is: Q=∑IRx1(t)+∑IRx2(t)+2×∑Iz(t)+2×Iy(t).

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